Warning: mysqli_connect(): php_network_getaddresses: getaddrinfo for db failed: Temporary failure in name resolution in /var/www/html/adminnew/include/modules/core.inc.php on line 19

Fatal error: Uncaught mysqli_sql_exception: php_network_getaddresses: getaddrinfo for db failed: Temporary failure in name resolution in /var/www/html/adminnew/include/modules/core.inc.php:19 Stack trace: #0 /var/www/html/adminnew/include/modules/core.inc.php(19): mysqli_connect('db', 'dev', Object(SensitiveParameterValue)) #1 /var/www/html/adminnew/include/functions.inc.php(14): include('/var/www/html/a...') #2 /var/www/html/inc/top.inc.php(2): include('/var/www/html/a...') #3 /var/www/html/index.php(2): require_once('/var/www/html/i...') #4 {main} thrown in /var/www/html/adminnew/include/modules/core.inc.php on line 19